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81 Cards in this Set
- Front
- Back
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What are the 6 functions of skeletal system?
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1) Support & attachment for tendons. 2) Protects vital organs. 3) Assists in movement - mm attach to bone. 4) Mineral homeostasis - stores calcium (99%) & phosphorus. 5) Blood cell production - red bone marrow produces RBC, WBC, platelets (process called hemopoiesis). 6) Triglyceride storage in adipose cells of yellow bone marrow.
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Describe the 4 steps of intramembranous ossification.
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1) Osteoblasts form ossification center & secrete extracellular matrix. 2) Calcification - ECM secretion stops & cells now osteocytes. 3) Develops into trabeculae & forms spongy bone. 3) Periosteum forms.
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Describe the 6 steps of endochondral ossification.
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1) Group chondroblasts secrete ECM & produce hyaline cartilage model. Perichondrium develops around it. 2) Chondrocyte division - interstitial growth (length) & appositional growth (thickness). 3) Primary ossification center develops (bone center) & trabeculae form. Spreads towards ends of cartilage model. 4) Osteoclasts carve medullary cavity. 5) Secondary ossification center forms - blood vessels invade. Cartilage goes to either end & repeats step 3. 6) Formation of articular cartilage.
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Describe the 4 steps of bone repair.
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1) Hematoma - blood clot forms (6-8hrs) & local damaged tissue removed by osteoclasts/phagocytes (2+ wks). 2) Fibrocartilaginous callus bridges gap b/w fracture (3 wks). 3) Bony callus formed by osteoblasts - make spongy bone. (3-4 mo) 4) Bone remodelling.
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Proximal & distal ends of bone.
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Epiphysis
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Region b/w diaphysis & epiphysis. Contains ___ ___ in growing bone, a layer of hyaline cartilage that allows bone to grow in length.
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Metaphysis. Epiphyseal plate.
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When bone stops growing b/w ages 18-21, cartilage in epiphyseal plate is replaced by bone. Resulting structure is called ___ ___.
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Epiphyseal line
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Thin layer of hyaline cartilage covering epiphysis where bone forms a joint. Reduces friction & absorbs shock at joints.
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Articular cartilage
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Surrounds external bone surface. Composed of outer fibrous layer (dense irregular connective tissue) & inner osteogenic layer (cells).
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Periosteum
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What are 5 functions of the periosteum?
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Enables bone to grow in thickness, protects, assists in fracture repair, nourish bone tissue, attachment point for ligaments & tendons.
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Collagen fibers that attach periosteum to underlying bone.
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Perforating (Sharpey's) fibers
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Hollow tunnel within diaphysis that contains fatty yellow bone marrow.
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Medullary (marrow) cavity
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Thin membrane that lines internal bone surface facing medullary cavity.
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Endosteum
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What forms the extracellular matrix of bone & in what ratios?
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25% water, 25% collagen fibers, 50% calcium phosphate (most abundant mineral)
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A bone's hardness depends on ___ while flexibility depends on ___.
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Crystallized salts. Collagen fibers.
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Type of stem cell derived from mesenchyme. Undergo cell division; resulting cell develop into osteoblasts.
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Osteogenic cell
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Type of bone-building cell. Synthesize extracellular matrix of bone & initiate calcification. (bone deposition)
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Osteoblast
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Type of mature bone cell that exchanges nutrients & wastes w/ blood.
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Osteocyte
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Large bone cell formed by fusion of many monocytes. Release enzymes that break down mineral content. (bone resorption)
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Osteoclast
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What % of the skeleton is compact vs. spongy?
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80% compact. 20% spongy.
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Why is bone resorption important?
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Necessary for development, maintenance, & repair of bone.
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Transverse hollow tunnel where blood/lymphatic vessels & nerves penetrate compact bone.
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Perforating (Volkmann) canal
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Hollow tunnel that runs vertically through bone.
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Central (haversian) canal
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What are the 3 types of lamellae & where are they found?
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Concentric (surround central canal). Interstitial (b/w osteons). Circumferential (encircle bone beneath periosteum & around medullary cavity).
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Calcified extracellular matrix. Area b/w osteons is ___ ___ while area encircling bone just beneath periosteum is ___ ___.
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Lamellae. Interstitial lamellae. Circumferential lamellae.
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Small space b/w lamellae containing osteocytes.
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Lacunae
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Extracellular fluid-filled channels connecting lacunae. Allow osteocytes to communicate via gap junctions & route for nutrient/oxygen/waste exchange.
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Canaliculi
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Repeating structural units in compact bone. Consists of central canal, lamellae, lacunae, osteocytes, canaliculi.
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Osteon
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How are osteons aligned in compact bone?
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Same direction as line of stress. Organization changes in response to physical demands placed on skeleton.
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Irregular lattice of thin columns in spongy bone.
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Trabeculae
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What type of bone tissue (spongy/compact) make up the interior of short, flat, & irregular shaped bones, & epiphyses of long bones?
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Spongy.
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What are 2 characteristics that differentiate spongy vs. compact bone?
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1) Spongy bone is light & improves movement. 2) Trabeculae support/protect red bone marrow. Site of hemopoiesis.
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In a bone scan, what do darker vs. lighter areas represent?
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Darker - increased metabolism. Lighter - decreased metabolism.
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Arteries that supply the periosteum & outer part of the compact bone. Enter bone through Volkmann's canals (perforations).
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Periosteal arteries
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Artery that passes through the nutrient foramen in the diaphysis and divides into proximal/distal branches. Supplies compact & spongy bone.
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Nutrient artery
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Arteries that enter metaphyses & supply red bone marrow & bone in metaphyses.
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Metaphyseal arteries
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Arteries that supply red bone marrow & bone in epiphyses.
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Epiphyseal arteries
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What are 4 veins that accompany the arteries of long bones?
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Nutrient, epiphyseal, metaphyseal, periosteal veins.
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Which part of the bone is rich in sensory nerves? What type of sensations does it mainly detect?
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Periosteum. Tearing, tension.
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Process by which bones form.
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Ossification
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What are the 4 situations of bone formation?
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Formation of bone in embryo (6th week), child growth until adulthood, bone remodelling (adult), fracture repair (adult)
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Type of ossification for flat bones. Forms directly within mesenchyme.
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Intramembranous ossification
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Type of ossification for long bones. Forms in hyaline cartilage derived from mesenchyme.
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Endochondral ossification
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Layer of hyaline cartilage in metaphysis responsible for lengthwise growth of long bones.
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Epiphyseal growth plate
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What are the 4 zones of growth in a growing bone?
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Resting (chondrocytes anchor epiphyseal plate), proliferating (increase # & secrete ECM - interstitial growth), hypertrophic, calcify (osteoclasts dissolve calcified cartilage, osteoblasts secrete bone ECM)
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At what age approx do the epiphyseal plates close in males vs. females?
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Females 18, males 21
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How do bones grow in thickness (appositional growth)?
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Cells in periosteum differentiate into osteoblasts which secrete ECM --> change to osteocytes & new osteons formed. Osteoclasts carve lining in medullary cavity (slower than outside growth).
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Ongoing replacement of old bone tissue by new bone tissue.
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Bone remodeling
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What is the difference b/w bone resorption vs. deposition?
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Bone resorption - breakdown of bone by osteoclasts. Deposition - bone building by osteoblasts.
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What are the benefits of bone remodelling?
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Removes injured bone, strengthen bone, change shape. New bone is more resistant to fracture than old bone.
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What factors can trigger bone remodelling?
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Exercise, sedentary lifestyle, changes in diet.
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Thick bumps on bone caused by too much bone deposition that can interfere w/ joint movement.
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Spurs
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Condition of abnormal acceleration of bone remodelling where new bone becomes hard, brittle, & fractures easily.
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Paget's disease
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What are 3 effects of an imbalance b/w osteoclasts & osteoblasts?
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Bones abnormally thick/heavy, excessive loss calcium causes osteoporosis, may become too flexible ie. Rickets/osteomalacia.
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Normal bone metabolism depends on what 3 factors?
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Vitamins, minerals, hormones
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What minerals are needed for bone metabolism?
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Calcium, phosphorus. Less of magnesium, fluoride, manganese.
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What vitamins are needed for bone metabolism?
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Vitamin ACDK & B12. A (stimulates osteoblasts), C (needed for collagen synthesis), D (increase absorption of Ca from GI tract), K & B12 (needed for bone protein synthesis)
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What hormones cause increase in osteoblasts, cause "growth spurt", then shut down epiphyseal growth plates?
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Estrogen, testosterone (sex hormones)
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Condition of oversecretion of hGH during childhood causes ___. Undersecretion of hGH is called ___. Oversecretion of hGH during adulthood is a condition called ___.
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Giantism. Pituitary dwarfism. Acromegaly.
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Type of fractures - broken ends of bone protrude from skin vs. one that doesn't break skin.
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Open (compound) fracture vs. closed (simple) fracture
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Type of fracture - bone is broken into pieces & smaller bone fragments lie b/w 2 main fragments. Most difficult type to treat.
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Comminuted fracture
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Type of fracture - partial fracture where 1 side of bone is broken & other side bends. Occurs mostly in children whose bones aren't fully ossified.
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Greenstick fracture
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Type of fracture - one end of fractured bone is forcefully driven into interior of other.
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Impacted fracture
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Type of fracture at distal end of fibula w/ serious injury of distal tibial joint.
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Pott's fracture
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Type of fracture at distal end of radius where distal fragment is displaced posteriorly.
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Colles' fracture
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Series of microscopic fissures in bone that form w/out any evidence of injury to other tissues. Result from repeated activities, ie. Running, jumping, dancing. Also osteoporosis. 25% involve tibia.
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Stress fracture
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Why does it sometimes take months for a fracture to heal?
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Calcium, phosphorus deposition is slow & bone cells grow/reproduce slowly.
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What are the 3 goals of fracture treatment?
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Realignment (open/closed reduction), immobilization to maintain alignment, restoration of function.
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What body functions depend on calcium homeostasis?
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Heartbeat (mm contraction), respiration, nerve cell functioning, enzyme functioning, blood clotting.
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What is the normal calcium range?
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9-11mg/100 ml
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What hormone (& origin) causes osteoclasts to break bone (resorption) to increase Ca2+ blood level in response to hypocalcemia? Also decrease Ca2+ loss in urine & stimulates formation of calcitriol to absorb Ca2+ in GI tract.
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Parathyroid hormone (PTH) <-- parathyroid gland
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What hormone (& origin) causes osteoblasts to build bone (deposition) to decrease Ca2+ blood level in response to hypercalcemia?
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Calcitonin <-- thyroid gland
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How do mechanical stresses strengthen bone?
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Through increased deposition of mineral salts & production of collagen fibers by osteoblasts.
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What are the 2 main mechanical stresses on bone? What type of activities strengthen bone?
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Those that result from pull of muscles & pull of gravity. Weight-bearing activities help build/retain bone mass, ie. Walking, weight lifting.
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Who is most affected by bone loss?
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Women after menopause - demineralization occurs sooner (age 30) than males & at a larger rate than males.
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What are the 2 main effects of aging on bone tissue?
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1) Loss of bone mass from demineralization (bone resorption outpaces deposition). 2) Brittleness - decreased protein synthesis & collagen fibers --> loss of tensile strength.
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Besides gender, what are risk factors for developing osteoporosis?
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Family history, european/asian ancestry, thin/small body build, inactive lifestyle, smoking, diet low in calcium/vitamin D, alcohol, certain meds.
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Bone's shaft or body
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Diaphysis
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Calcium phosphate combines w/ calcium hydroxide to form crystals of ___. These then combine w/ more minerals.
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Hydroxyapatite
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Ossification occurs in what week within the uterus?
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6th week
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What type of ossification forms flat vs. Long bones?
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Flat - intramembranous. Long - endochondral.
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